Bachelor project consisting in implementing a thermal response test (TRT) in BHE VIA14 placed in the energy park of VIA University College (Horsens), analyzing the results and modeling the BHE in FEFLOW software.

1. VIA University
College
Thermal response test and
soil geothermal modelling
Authors:
Pedro Rico López
Miguel Salgado Pérez
David Canosa Vaamonde
Martín Amado Pousa
Supervisors:
María Pagola
Inga Sorensen
Henrik Bjørn
1

2. 1. INTRODUCTION
Text
VIA University
College
Via University
College
2
Energy park
LOCATION

3. 1. INTRODUCTION
VIA University
College
3
LOCATION
ENERGY PARK

4. VIA University
College
4
1. INTRODUCTION
ENERGY PARK
LOCATION

5. VIA University
College
5
1. INTRODUCTION
ENERGY PARK
ENERGY PARK

6. VIA University
College
6
1. INTRODUCTION
LOCATION
ENERGY PARK

7. VIA University
College
7
1. INTRODUCTION
LOCATION
VIA 14 VIA 13
ENERGY PARK

8. VIA University
College
8
1. INTRODUCTION
BOREHOLE DESCRIPTION
VIA 14 VIA 13
100m 96m
VIA 14
10m

9. 1. INTRODUCTION
TRT in BHE VIA 14
Thermal energy storage modelling with Feflow
VIA University
College
9
GOALS
GeRT
VIA 14

10. 1. INTRODUCTION
TRT in BHE via 14
-Thermal conductivity of the soil around of BHE VIA 14
-Borehole thermal resistance of the BHE VIA 14
Outcomes
VIA University
College
10
GOALS
Interpreted
Compared
Previous TRT
By intervals of time
GeRT software
Conclusions

11. 1. INTRODUCTION
•Thermal modelling by feflow software
VIA University
College
11
GOALS
Behavior
of the soil
Storage Extraction

12. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
12
Shallow geothermal energy
Energy stored in the form of heat
beneath the surface of the solid
earth.
Solar = 1 MWh/m²
Geothermal = 0,5 – 1 kWh/m²
Solar : Geothermal = 1000 : 1
Shallow energy = Solar energy

13. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
13
Shallow geothermal energy
• How much energy can be extracted depends on:
Heat transfer:
• Conduction
• Convection
• Advection
• Dispersion
• Radiation
Geothermal gradient:
• 2,5 – 3,0 ºC/100m
Properties of soil:
• Specific heat capacity
• Thermal conductivity
• Diffusivity
Conductive heat flow:
• 65 – 101 mW/m²

14. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
14
Ground Source Heat Pump
Ground source

15. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
15
Ground source heat pump system
The heat transfer
is done through
heat exchanger
Ground water heat pump system (open loops)
Close loops system

16. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
16
Borehole heat exchanger
Ø 75-200 mm
30-300m depth

17. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
17
Borehole heat exchanger
Configuration

18. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
18
Borehole thermal resistance
The thermal resistance [K m W-1] is the capacity of any material
to oppose to heat transfer through itself
Surrounding ground
thermal resistance Rg
Borehole thermal
resistance
Rb= Rf + Rbhf+ Rbhw

19. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
19
Borehole thermal resistance
Parameter Influencing thermal resistance
•Number of pipes
•Borehole depth
•Shank spacing (distance between pipes)
•Pipe material
•Fluid flow rate

20. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
20
TRT Definition
The thermal response test is a suitable method to
determine the effective thermal conductivity of the
underground and the borehole thermal resistance
(Gehlin 2002).
Mogensen (1983) presented a method measure the
thermal properties of boreholes in situ, the thermal
response test.
Mogensen designed a system where a fluid is circulated
through the BHE. TRT method is based in the principle that
with a known input power and tracking the mean
temperature development over time, it is possible to
measure the heat transported to the ground.

21. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
21
Thermal response test TRT
Steps before TRT:
•Estimate thermal conductivity (λ) and volumetric heat
capacity of the ground (Rb).
•Measure the undisturbed ground temperature.

22. 2. BIBLIOGRAPHIC RESEARCH
VIA University
College
22
Underground thermal energy storage (UTES)
• Use of borehole heat
exchangers
• Depends on the thermal properties
of the ground.
• Can be used to balance heating
systems STES

23. 3. EXPERIMENTAL SECTION VIA University
College
23
PROCESS SUMARY
• Thermal properties estimation.
• Undisturbed ground temperature.
• Thermal Response Test.

24. 3. EXPERIMENTAL SECTION
• Literature values from VDI
• Geological information (GEUS)
• Previous results of needle prove tests
VIA University
College
24
THERMAL PROPERTIES ESTIMATION

25. VIA University
College
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3. EXPERIMENTAL SECTION
THERMAL PROPERTIES ESTIMATION
Depth (m) Layer
thickness
(m)
λ (W/mK)
Svc
From To (MJ/m³K)
1 3 2,0 1,54 2,40
3 6 3,0 1,00 1,60
6 9 3,0 2,36 2,20
9 12 3,0 1,40 1,90
12 15 3,0 1,00 1,50
15 18 3,0 2,35 2,50
18 24 6,0 1,40 1,90
24 27 3,0 1,74 2,40
27 45 18,0 1,00 2,00
45 48 3,0 1,31 2,00
48 51 3,0 1,10 2,00
51 54 3,0 1,80 2,40
54 57 3,0 2,40 2,50
57 100 43,0 1,00 2,00
Total depth (m) 99,0
λ(ari) Svc(ari)
1,23 2,03
Arithmetic mixing model;

26. 3. EXPERIMENTAL SECTION
Thermal conductivity:
Volumetric heat capacity:
λ= 1,23 W/m/K
VIA University
College
Svc= 2,03 MJ/m³/K
26
THERMAL PROPERTIES ESTIMATION
• This values are not a good estimation
• λ Significantly lower than real
• Only to calculate break time for steady state

27. VIA University
College
27
3. EXPERIMENTAL SECTION
UNDISTURBED GROUND TEMPERATURE
A good estimate of the undisturbed ground
temperature is necessary for a correct design of the
ground heat exchanger (Gehlin 2002).
• At the same time the authors measured the
ground water table at 15,05m.

28. VIA University
College
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3. EXPERIMENTAL SECTION
UNDISTURBED GROUND TEMPERATURE
The method performed was:
• Measure temperature in each meter of depth.
• 4 minutes interval between steps.
• The average temperature calculated with the
arithmetic mean.

29. VIA University
College
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3. EXPERIMENTAL SECTION
UNDISTURBED GROUND TEMPERATURE
The undisturbed ground
temperature mean result was
9,56 ºC
0 5 10 15
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
Temperature (Cº)
Depth
(m)

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College
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3. EXPERIMENTAL SECTION
THERMAL RESPONSE TEST
Analysis method – Line Source Theory

31. VIA University
College
31
3. EXPERIMENTAL SECTION
THERMAL RESPONSE TEST
Experimental setup for TRT
• Equipment
- New equipment GeRT by UBeG
- Safety control systems
- Own software

32. VIA University
College
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3. EXPERIMENTAL SECTION
THERMAL RESPONSE TEST
Experimental setup for TRT
• Initial assumptions
- Temperature of soil in equilibrium
- Insulate the pipes
- Pressure between 1 and 2 bar
- Turbulent flow Re 4000
- Heat power of 30-80 W/m
- Length minimum 50 h

33. VIA University
College
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3. EXPERIMENTAL SECTION
THERMAL RESPONSE TEST
Experimental setup for TRT
• Calculations
- Total duration: 50,8 h
- Reynolds number: 17020
- Heat input rate: 58 w/m
- Initial ti: 9,6 ºC
- Final tf: 24,9 ºC
Starting values Final values
Input
temperature
9,62 ºC 26,56 ºC
Output
temperature
9,63 ºC 23,43 ºC
Selected hea
ting power
75% -
Date 07/04/2014 09/04/2014
Time 11:03 13:00
Actual
heating
5,8 Kw 5,7 Kw
power
Flow rate 1,572 m3/h 1,572 m3/h
Total flow
283,90 m3 361,94 m3
volume
Total electric
work
673 Kwh 958 Kwh
Pressure 2 bar 2 bar

34. VIA University
College
34
3. EXPERIMENTAL SECTION
THERMAL RESPONSE TEST
Experimental setup for TRT
• Calculations
- Length minimum 50 h
- Dismissing time
- Time intervals
VIA 14 CALCULATIONS
Time
interval
6h-50h 9h-50h 12h-50h 9h-45h 9h-40h

35. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
35
Results
30,00
25,00
20,00
15,00
10,00
5,00
Undisturbed Ground
Temperature (°C)
Tf(°C) LHS (°C) Effect (kW) Flow (m³/h)
Mean power rate input
(W/m)
Thermal Conductivity
(W/mK)
Borehole Thermal
Resistance (mK/W)
9,56 56,85 2,03 ± 0,03 0,1079 ± 0,0020
0,00
0 5 10 15 20 25 30 35 40 45 50 55
Time (h)

36. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
36
Temperature (ºC) Linear (Temperature (ºC))
y = 2,2229x - 1,9832
25,50
25,00
24,50
24,00
23,50
23,00
22,50
22,00
21,50
21,00
20,50
10,25 10,50 10,75 11,00 11,25 11,50 11,75 12,00 12,25
Temperature (ºC)
Time ln(s)

37. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
37

38. According line source theory:

39. 0,1500
0,1450
0,1400
0,1350
0,1300
0,1250
0,1200
0,1150
0,1100
0,1050
0,1000
0,0950
0,0900
0,0850
0,0800
0,0750
4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
2,25
2,20
2,15
2,10
2,05
2,00
1,95
1,90
1,85
1,80
1,75
1,70
1,65
1,60
1,55
1,50
7,5 12,5 17,5 22,5 27,5 32,5 37,5 42,5 47,5 52,5
Thermal resistance (mK/w)
Thermal conductivity (W/mK)
Time (h)
Soil thermal conductivity (w/mK) Borehole thermal resistance (mK/w)
VIA University
College
38
λmean = 2,03 ± 0,03 w/mK
Rbmean = 0,1079 ± 0,0020 mK/w

40. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
39
Comparison time intervals
Time
interval (h)
6-50 9-50 12-50 9-45 9-40
Thermal
Conductivity
(W/mK)
2,00 ± 0,03 2,03 ± 0,03 2,08 ± 0,03 2,05 ± 0,03 2,03 ± 0,03
Borehole
Thermal
Resistance
(mK/W)
0,1060 ± 0,0020 0,1079 ± 0,0020 0,1101 ± 0,0020 0,1088 ± 0,0019 0,1079 ± 0,0019
According Sanner (2005) and Banks (2012):
∝
= 8,89 hours

41. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
40
y = 2,2643ln(x) + 16,076
y = 2,2229ln(x) + 16,219
y = 2,1768ln(x) + 16,381
25,00
24,50
24,00
23,50
23,00
22,50
22,00
21,50
21,00
20,50
20,00
5,00 50,00
Temperature (°C)
Time logarithm (h)
Trend Line (6-50h) Trend Line (9-50h) Trend Line (12-50h)

42. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
41
Comparison GeRT software

43. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
42

44. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
43
Time interval
(h)
Manual
calculation
GeRT
calculation
Neglected time
(h)
9,00 8,96
Thermal
Conductivity
(W/mK)
2,03 2,01
Borehole Thermal
Resistance
(mK/W)
0,1079 0,1090
Error in manual results ≈ 1%

45. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
44
Comparison with previous TRT
Time interval (h) Past TRT Current TRT
Starting Date 03/07/2013 07/04/2014
Starting time 18:00 10:10
Finishing date 07/07/2013 09/04/2014
Finishing time 16:33 13:00
Total duration (h) 51,25 50,8
Undisturbed ground
9,90 9,56
temperature (ºC)
Groundwater level (m) 15,15 15,05
Average heating
power (w)
2180 5626
Average flow rate (l/h) 1121,70 1554,75

46. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
45
27,5
25,0
22,5
20,0
17,5
15,0
12,5
10,0
7,5
5,0
2,5
0,0
-5 0 5 10 15 20 25 30 35 40 45 50 55
Time (h)
Past TRT temperature (ºC) Current TRT temperature (ºC) Past TRT power (Kw) Current TRT power (Kw)

47. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
y = 2,2229x - 1,9832
y = 0,9748x + 4,356
46
26
25
24
23
22
21
20
19
18
17
16
15
14
10,25 10,50 10,75 11,00 11,25 11,50 11,75 12,00 12,25
Temperature (ºC)
ln (s)
Past TRT Present TRT Linear (Past TRT) Linear (Present TRT)

48. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
0,15
0,14
0,13
0,12
0,11
0,10
47
2,25
2,00
1,75
1,50
1,25
1,00
9 14 19 24 29 34 39 44 49 54
Borehole thermal resistance (mK/w)
Soil thermal conductivity (w/mK)
Time (h)
λ past TRT λ present TRT Rb past TRT Rb Present TRT

49. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
48
Results Previous TRT Current TRT
Heating power
Flow rate
≈ Constant in both TRT
Presence of air
in the loop
Thermal Conductivity
(W/mK)
1,75 ± 0,05 2,03 ± 0,03
Borehole Thermal
Resistance (mK/W)
0,1128 ± 0,0049 0,1079 ± 0,0020
λpast TRT
too variable

50. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
49
Comparison with FEFLOW model
λ (w/mK) 2,03
Svc (MJ/m3K) 2,03
Temperature (ºC) 9,56
Area (m2) 20 x 20
Depth (m) 120
Groundwater
flow
Neglected

51. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
50
Time
interval
(h)
λ grouting
(w/m·K)
Shank
spacing
(mm)
Svc soil
(MJ/m3·K)
Model 1 2,35 80 2,03
Model 2 1,50 80 2,03
Model 3 1,50 60 2,03
Model 4 1,50 60 3,00

52. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
51
27
25
23
21
19
17
15
13
11
9
0 5 10 15 20 25 30 35 40 45 50 55
Temperature (ºC)
Time (h)
TRT Model 1 Model 2 Model 3 Model 4

53. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
52
Before starting TRT After finishing TRT

54. 4. RESULTS, INTERPRETATION AND
COMPARIONS OF TRT
VIA University
College
53

55. 5. THERMAL ENERGY STORAGE
ENERGY STORAGE IN VIA 14 AND EXTRACTION IN VIA 13
Soil data assumed:
• λ = 2,03 W/mK (real value of TRT)
• Svc = 2,03 MJ/m²K (literature value)
• Homogeneous characteristics
• Groundwater flow neglected
Thermal energy storage data assumed:
• Maximum soil temperature = 20 ºC
Thermal energy extraction data assumed:
• Minimum soil temperature = 0 ºC
VIA University
College
54

56. 5. THERMAL ENERGY STORAGE
Thermal energy extraction in BHE VIA 13
VIA University
College
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Svc CALCULATIONS
ΔT (K) Radius (m) Volume (m³) Energy (MJ) Energy(MWh)
-9,56 3,40 3486 -67660 -18,794
Svc 3,45 3590 -69665 -19,351
(MJ/m³K) 3,50 3695 -71699 -19,916
2,03 3,55 3801 -73762 -20,489
BHE depth 3,60 3909 -75854 -21,071
(m) 3,65 4018 -77976 -21,660
96 3,70 4129 -80127 -22,257
Taking into account a radio around the borehole between 3,50 and 3,55
m, the amount of energy can be extracted is between 19, and 20,5 MWh

57. 5. THERMAL ENERGY STORAGE
Thermal energy storage in BHE VIA 14
VIA University
College
56
Svc CALCULATIONS
ΔT (K) Radius (m) Volume (m³) Energy (MJ) Energy(MWh)
-9,56 3,10 3019 63984 17,773
Svc 3,20 3217 68178 18,938
(MJ/m³K) 3,30 3421 72506 20,141
2,03 3,40 3630 76997 21,380
BHE depth 3,45 3739 79247 22,013
(m) 3,50 3848 81561 22,656
96 3,60 4072 86288 23,969
Taking into account a soil radio around the borehole between 3,40 and
3,45 m, the amount of energy can be stored is between 21,4 and 22,0 MWh

58. 5. THERMAL ENERGY STORAGE
· G · G · ·
VIA University
College
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INFINITE LINE SOURCE METHOD
Applying Fourier’s Law in each direction
and assuming that the thermal process
depends only on the radial distance:
Integrating the previous formula and
assuming that the temperature in the
system at the beginning (t=0) and in the
surroundings located at infinite distance
from the heat source (r=∞) is constant
(t0=undisturbed ground temperature)

59. VIA University
College
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5. THERMAL ENERGY STORAGE
Heat energy extraction in BHE VIA 13
Previous premises:
• Minimum soil temperature in storage (Tf)
• Undisturbed ground temperature (T0)
• Time = 1 year
Heat energy extraction (BHE VIA 13)
r (m) λ
(W/m K)
Rb
(m K/W)
SVC
(J/m³ K)
a (m²/s) Tf (ºC) T0 (ºC) γ (Euler’s
constant)
0,16 2,03 0,0899 2030000 0,000001 0,0 9,56 0,5772157
Isolating from the LS formula:
• q: heat flux (W/m)
• Q: amount of heat energy extracted (MWh)

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Heat energy extraction in BHE VIA 13
Heat energy storage
along 1 year
Q = - 20,07 MWh
5. THERMAL ENERGY STORAGE

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5. THERMAL ENERGY STORAGE
Heat energy storage in BHE VIA 14
Previous premises:
• Minimum soil temperature in storage (Tf)
• Undisturbed ground temperature (T0)
• Time = 1 year
Heat energy extraction (BHE VIA 13)
r (m) λ
(W/m K)
Rb
(m K/W)
SVC
(J/m³ K)
a (m²/s) Tf (ºC) T0 (ºC) γ (Euler’s
constant)
0,16 2,03 0,1079 2030000 0,000001 20,0 9,56 0,5772157
Isolating from the LS formula:
• q: heat flux (W/m)
• Q: amount of heat energy extracted (MWh)

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Heat energy storage in BHE VIA 14
Heat energy storage
along 1 year
Q = 21,85 MWh
5. THERMAL ENERGY STORAGE

63. VIA University
College
5. THERMAL ENERGY STORAGE
ENERGY STORAGE IN VIA 14 AND EXTRACTION IN VIA 13
62
FEFLOW geothermal modelling
Theoretical situation model:
• Heat energy extraction through BHE VIA 13
• Heat energy storage through BHE VIA 14
• Time of simulation: 1 year
• Time step of simulation: 10-7seconds
• Heat flux (W/m) obtained from LS model per day during 1 year
• Minimum flow rate to obtain turbulent flow
• Soil data assumed:
• λ = 2,03 W/mK (real value of TRT)
• Svc = 2,03 MJ/m²K (literature value)
• Homogeneous characteristics along depth (groundwater flow neglected)
• Undisturbed ground temperature (9,56 ºC)

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5. THERMAL ENERGY STORAGE
FEFLOW extraction and storage model
The evolution of the BHEs temperatures is according to the main premises
established before de calculation of the heat flux along the year.

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5. THERMAL ENERGY STORAGE
FEFLOW extraction and storage model
Soil temperature behaviour along 1 year

66. VIA University
College
5. THERMAL ENERGY STORAGE
Influence on the soil temperature of the heat energy extraction through the BHE
VIA 13 and the heat energy storage to BHE VIA 14 along 1 year.
• NO heat transfer between the BHE during 1 year.
65
FEFLOW extraction and storage model

67. VIA University
College
5. THERMAL ENERGY STORAGE
SEASONAL THERMAL ENERGY STORAGE IN BHE VIA 14
66
Theoretical heating system model:
• Heat energy consumption of the World Flex House in Energy Park
(heating system and DHW)
• Heat pump (COP = 4,65) connected to the BEH VIA 14 and
thermal solar panels
• Four 2,5 m² area and 0,79 of optical efficiency thermal solar
panels
• Excess production of thermal solar panels is stored within the soil
through the BHE

68. VIA University
College
5. THERMAL ENERGY STORAGE
SEASONAL THERMAL ENERGY STORAGE IN BHE VIA 14
67
Thermal solar panels Heat pump (COP = 4,65)
Sun radiation
(kWh/m²)
Heat energy
production (kWh)
Storage: excess
production (kWh)
Consumption
(kWh)
Extraction
(kWh)
Jan 29,1 166,3 0,0 1501,7 1235,9
Feb 44,8 256,1 0,0 960,9 790,8
Mar 112,0 640,2 0,0 247,8 203,9
Apr 158,0 903,2 506,2 0,0 0,0
May 174,0 994,7 794,7 0,0 0,0
Jun 170,0 971,8 771,8 0,0 0,0
Jul 167,0 984,6 754,6 0,0 0,0
Aug 152,0 868,9 668,9 0,0 0,0
Spe 119,0 680,3 282,3 0,0 0,0
Oct 78,7 449,9 41,9 0,0 0,0
Nov 37,8 216,1 0,0 875,9 720,9
Dec 23,5 134,3 0,0 1497,7 1232,6
YEAR 1265,9 4824,3 3820,3 5083,9 4184,1

69. VIA University
College
5. THERMAL ENERGY STORAGE
BHE temperatures evolution along the year
• Heat energy extraction in winter months
• Heat energy storage in summer months
68
FEFLOW heating system model along 1 year

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model along 1 year
Soil temperature behaviour along 1 year

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model
Temperature of the soil in 31th of January
This figure shows the cooling of the ground after the first month of heat energy
extraction

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model
Temperature of the soil in 31th of May
This figure shows how the temperature of the ground is balanced after the
second month of heat energy storage

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model
Temperature of the soil in 30th of September
This figure shows the heating of the temperature of the ground after the heat
storage season

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model
Temperature of the soil in 31th of December
This figure shows the cooling of the ground after the second month of heat
energy extraction

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model along 3 years
BHE temperatures evolution along 3 year
• Heat energy extraction in winter months
• Heat energy storage in summer months

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model along 3 years
Stored heat energy into the soil obtained from FEFLOW

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5. THERMAL ENERGY STORAGE
FEFLOW heating system model along 3 years
Stored heat energy into the soil influence:
• Heat energy extraction: 12552,3 MWh
• Heat energy storage: 11460,9 MWh
• Stored heat energy into the soil drops 2300 MWh after 3 years
• FEEFLOW theoretical heat energy storage
12552,3 – 2300 = 10252,3 MWh
• Efficiency of the thermal energy storage = 89,5 %

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5. THERMAL ENERGY STORAGE
INTERPRETATION OR RESULTS
Heat energy extraction in BHE VIA 13
• Line source model: 20,07 MWh during 1 year
• Cooling from 9,56 ºC to 0 ºC of a cylinder of soil with radio
between 3,50 and 3,55 m
• Soil is an infinite medium: After 1 year, around 1 m of the BHE, the
temperature soil drops until 4,0 ºC
Heat energy storage in BHE VIA 14
• Line source model: 21,85 MWh during 1 year
• Heating from 9,56 ºC to 20 ºC of a cylinder of soil with radio
between 3,40 and 3,45 m
• After 1 year, considering the influence around 1 m of the BHE, the
temperature soil increases until 13,5 ºC

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5. THERMAL ENERGY STORAGE
INTERPRETATION OR RESULTS
Seasonal energy storage in BHE VIA 14
• The ground source heat pump system efficiency improves
(higher flow temperatures)
• Soil temperatures are balanced along the time (NO freezing
problems within the soil)
• Heat energy stored into the soil along the time is balanced

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6. CONCLUSIONS AND
FURTHER RESEARCH
• VIA University is a leading university researching about
shallow geothermal energy
• VIA has great facilities to develop research projects
• For TRT, Svc estimation is one of the main problems leaving
the door open to research in this field
• Use of real data of Energy Park installations in further projects
and compare FEFLOW simulations with real experiments
• Take into consideration more data (ground water flow)
• Implement better managing procedures for the
collaboration between project group researches

81. Thank you for your attention
Contact info:
Pedro Rico López – pedroricolopez@hotmail.com
Miguel Salgado Pérez – jmsalgadoperez@gmail.com
David Canosa Vaamonde – david.canosa@udc.es
Martín Amado Pousa – martinamadopousa@gmail.com
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